The present invention relates to bullet-proof and/or shatter-proof toughened, laminated plate glass, which may be used to protect road vehicles, rolling stock, sea-going vessels or aircraft. In particular, the glass may be used in motor vehicles such as armored cars and military vehicles, as well as security vans for transporting cash. However, the toughened, laminated plate glass of the present invention may also be used to protect buildings. This glazing may also be fixed or mobile.
A great deal of effort has gone into improving, armored glass, in particular with a view to increasing it""s the ability of the glass to withstand increasingly high-performance bullets and more powerful impacts concentrated on a small surface area.
In a previous attempt to improve the ballistic performance of glass of this type, the present applicant proposed a bullet-proof and/or shatter-proof toughened, laminated glass in French patent application FR-A-2 764 841, in which one or more rigid excrescences were formed on at least a part of a periphery, each substantially belonging to a plane parallel with the surface defined by the plate glass or with the extension of this surface and being of a thickness such that it could be introduced, at least partially, temporarily or permanently, into the rebate of the glazing aperture.
The strongest embodiment described in said French patent application FR-A-2 764 841 is the one illustrated in FIG. 4 of the publication. It consists, from the outside to the inside (in the present description, the outside end is the end from which the impact is likely to occur), of:
{circle around (1)} a sheet of chemically reinforced glass or a stack comprising a sheet of glass, an intermediate adhesive layer of polyvinyl butyral (PVB), and a sheet of glass; and
{circle around (2)} a stack of sheets made up of:
{circle around (2)}a an intermediate adhesive layer of PVB;
{circle around (2)}b sheet of glass;
{circle around (2)}c an intermediate adhesive layer of PVB,
{circle around (2)}d sheet of glass;
{circle around (2)}e an intermediate adhesive layer of polyurethane (PU); and
{circle around (2)}f a sheet of polycarbonate, the inside face of which is generally coated with an anti-scratch lacquer.
The surface area of stack {circle around (2)} is smaller than that of the sheet or stack {circle around (2)} so that the periphery of this sheet or stack {circle around (1)} extends uniformly beyond that of stack {circle around (2)}. A peripheral band is applied against the periphery of sheet or stack {circle around (1)}, and the band is joined, by bonding for example, to the inside face of the sheet or stack {circle around (1)} projecting beyond the stack {circle around (2)}. This peripheral band is also joined at its inner edge, for example by bonding, to the outer edge of the stack {circle around (2)}, against which it is supported.
The unit comprising the peripheral band and the peripheral zone of the sheet or stack {circle around (1)} may be inserted in a rebate of an aperture or simply placed so that it is supported thereon and nested to a greater or lesser degree relative to the structure of this aperture, directed towards the outside, depending on the shapes of aperture used.
A toughened, laminated plate glass made in this way has two juxtaposed ballistic systems. In particular, the glass has a first, central ballistic system constituted by stack {circle around (2)} and the central zone of the sheet {circle around (1)} or stack {circle around (1)} facing the stack {circle around (2)}; and a second, peripheral ballistic system, formed by the peripheral band and the peripheral region of the sheet {circle around (1)} or stack {circle around (1)} facing the peripheral band.
The toughened, laminated glass pane proposed in the French application is totally satisfactory compared with known armored glass in terms of withstanding higher-performance projectiles and more powerful and more numerous impacts, regardless of whether they are simultaneous or consecutive. However, this toughened, laminated glass pane has a weak spot in the edge region. In other words, there is a weak spot in the zone at which the two ballistic systems described above (central and peripheral) meet. In practice, this zone may be in the order of 0.5 to 3 cm in width and a marksman can therefore aim for and hit it.
It goes without saying that this weak spot in the edge region needs to be eliminated in the most radical way possible, especially as the excrescence by which the pane is inserted in its rebate is small in height (in the order of 1 to a few cm in the case of car windows), and given that it is not desirable to use a reinforcement overlapped by the structure supporting the glazing (bodywork) so as to avoid losing window light and for reasons of cost.
The present invention meets this objective. To this end, it is proposed that the reinforcing element (band), having a high ballistic strength and forming part of the second ballistic system be extended towards the center in order to form at least one ballistic layer which integrates with the first ballistic system over a length likely to cover the edge region that is less well protected. Consequently, it has been found possible to use embodiments of various shapes in order to meet specific protection requirements (in particular, to reinforce this protection), and also to adapt the toughened laminated glass to existing chassis designs (in particular, to meet the thickness constraints of aperture rebates on cars).
Accordingly, the present invention relates to a pane of bullet-proof and/or shatter-proof toughened, laminated glass, in which a part of the stack comprising the pane extends, on at least a part of the periphery of the pane, beyond the rest of the stack. Thus, an excrescence against which the reinforcing element made from a high-strength ballistic material can be applied, from the inside if the impact is likely to be generated from the outside, is formed integral with the pane. The pane of glass includes a peripheral ballistic system (BP), formed by the excrescence and the band (C), so that the pane can be mounted in the rebate of the structure designed to bear the pane. The rest of the pane thus forms a central ballistic system (BC). In this regard, the term xe2x80x9ccenterxe2x80x9d or xe2x80x9ccentralxe2x80x9d as used herein refer to the center of a plate glass (pane) with respect to a geometric plane of the plate glass (pane). The central ballistic system (BC) has, at its peripheral region corresponding to that of the reinforcing element (C) of the peripheral ballistic system (BP), one or more reinforcing layers of cladding made from a high-strength ballistic material and integrated in the stack constituting the pane. The single reinforcing layer of cladding, or at least one of the reinforcing layers of cladding if there are or more than one, is joined to the element (C).
The peripheral region of the central ballistic system (BC) corresponding to that of the reinforcing element (C) of the peripheral ballistic system (BP) does not generally have a reinforcing layer of cladding on the external side of the pane relative to the band (C).
In a particularly preferred manner, the toughened, laminated plate glass of the invention is made up of a stack of sheets of glass alternating with intermediate adhesive layers, starting with a sheet of glass on the outer side and terminating on the inner side also with a sheet of glass. In this regard, the terms xe2x80x9cinnerxe2x80x9d and xe2x80x9couterxe2x80x9d as used herein refer to the sides of the glass plate as installed. In contrast, the term xe2x80x9cinternalxe2x80x9d refers to a location within the glass plate (e.g., between two adjacent sheets of glass), while the term xe2x80x9cexternalxe2x80x9d refers to a location not within the glass plate. The reinforcing element (C), the reinforcing layer or layers of cladding (cladding portions) and, if applicable, the linking elements between the element (C) and the reinforcing layer or layers of cladding are integrated in the glass plate by one or more intermediate adhesive layers or by some of the layers, or of an intermediate adhesive material, such as the same type as that constituting the intermediate adhesive layers.